Bone is a dynamic tissue, consisting of cells in a protein matrix, upon which is superimposed a crystalline structure of various calcium salts. Bone injury can occur in a variety of manners, for example, a bone fracture, can be caused by excessive force being exerted onto the bone, and bone degeneration can be caused by a relative excess of bone resorption as occurs, for example, with osteoporosis. Regardless of the type of bone injury, it can create substantial problems because bone is the primary support for the body of an animal.
In addition to serving as a rigid support for the body of an animal, bone is an organ which responds to various agents, including hormones, some of which have the ability to increase bone formation or inhibit bone resorption. However, many agents having the capacity to treat or prevent bone injury or metabolic disorders based on their ability to promote bone formation or inhibit bone resorption cannot be effectively used because they lack any bone specificity.
Thus, there remains a need in the art for compounds and methods for imparting bone specificity to agents having the capacity to treat or prevent bone injury or metabolic disorders based on their ability to promote bone formation or inhibit bone resportion.